This application is based on and claims priority under 35 U.S.C. xc2xa7119 with respect to Japanese Application No. 2000-238094 filed on Aug. 7, 2000, the entire content of which is incorporated herein by reference.
This invention generally relates to a gear shifting control device. More particularly, the present invention pertains to a gear shifting control device for a synchromesh transmission and actuation thereof.
As a type of transmission for transmitting rpm from a vehicle power source to the driving wheels, a synchromesh transmission is known. In the synchromesh transmission, sliding elements do not exist in the power transmitting system from the power source to the driving wheels. Accordingly, the synchromesh transmission has advantages in that the driving wheels sensitively respond to the accelerating operation of the driver to obtain a driving feeling with good response, and in that the fuel consumption is reduced to contribute to saving energy.
To obtain the aforementioned advantages and to simplify the shifting operation by the driver compared to conventional manual transmissions, Japanese Patent Laid-Open Publication No. 2000-46176 discloses a gear shifting control device for varying the shift ratio of a synchromesh transmission by an electrically controlled actuator.
The transmission used along with a gear shifting control device of this kind includes a synchronizer for selecting one of a plurality of gear mates wherein respective gear mates are always intermeshed and wherein the gear ratios are different from one another as effective gear mate (in order to obtain a predetermined gear ratio). The synchronizer includes a sleeve and a synchronizer ring. The sleeve is relatively movable in an axial direction and is non-rotatable relative to a shaft to which one gear of the gear mates is relatively rotatably equipped as an idling gear. The synchronizer ring is relatively rotatable to the idling gear and relatively movable in an axial direction.
When the foregoing synchronizer is under operation, the sleeve is moved in the axial direction to be contacted to the synchronizer ring. Thus, the idling gear and the sleeve are synchronized by pressing the synchronizer ring to a frictional surface which is rotatable with (relatively non-rotatable) the idling gear. The synchronizer balks the intermeshing of a first clutch unitary rotating with (i.e., relatively non-rotatable to) the sleeve with a second clutch unitary rotating with (i.e., relatively non-rotatable to) the idling gear.
The foregoing gear shifting control device further includes an actuator, a transmitting mechanism, and a controller. The actuator generates a load for moving the sleeve in the axial direction. The transmitting mechanism transmits the load generated by the actuator to the sleeve. The controller controls an actuator for varying the shift ratio of the transmission based on at least one of: an intention of the driver, the vehicle condition, and the condition of the transmission.
In the gear shifting control device of this kind, a load transmitting system for transmitting the load from the actuator to the sleeve via the transmitting mechanism may include an inertial element and a spring element.
In this case, it is necessary to change an actual (current) value of the sleeve load to a required value (target value) different from the actual value. When a step signal is supplied to the actuator, a transient state occurs in the sleeve load during the period from the start of supply of the step signal until the period that the actual value of the sleeve load reaches the required value. The load under this transient state is called a surge load.
The surge load sometimes exceeds the required value of the sleeve load. The excessive surge load generates unpleasant noise and physical shock to the driver at a shift change of the transmission. Such excessive surge load may cause damage to the synchronizer ring.
A need exists for a gear shifting control device which controls the actuator to more accurately adjust the actual value of the sleeve load to the required value.
In light of the foregoing, the present invention provides a gear shifting control device for synchromesh transmission transmitting a rotation of a power source to driving wheels which includes a gear mate always intermeshed and a synchronizer for selecting one of a plurality of gear mates having different gear ratios from one another as an effective gear mate. The synchronizer includes a shaft, with one gear of the gear mate being relatively rotatably equipped thereon as an idling gear, a sleeve relatively non-rotatable to the shaft and relatively movable in axial direction, a synchronizer ring relatively rotatable to the idling gear and relatively movable in an axial direction, a frictional surface relatively non-rotatable to the idling gear, a first clutch relatively non-rotatable to the sleeve, and a second clutch relatively non-rotatable to the idling gear. The sleeve is moved in an axial direction to contact the synchronizer ring. The idling gear and the sleeve are synchronized by pressing the synchronizer ring to the frictional surface. The first clutch and the second clutch are balked relative to one another until the synchronization between the sleeve and idling gear.
The gear shifting control device for a synchromesh transmission further includes an actuator for generating a load for moving the sleeve in the axial direction and electrically controlled in accordance with an external signal, a transmitting mechanism for transmitting the generated load by the actuator to the sleeve, and a controller for controlling the actuator for varying the gear ratio of the transmission based on at least one of a driver""s intention, vehicle condition, and condition of the transmission, the controller supplying a driving signal continuously varying in accordance with time to the actuator when necessary to change an actual value of sleeve load operating the sleeve to a required value different from a current value.